Remove unused .tabmodel members of TabSwitcherButtonCoordinator

Change-Id: Ie8e9ea00b30200f4cff054060fc76cff7fbc4623
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2176759Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#768438}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherButtonCoordinator.java

@@ -12,9 +12,6 @@ import org.chromium.chrome.browser.ThemeColorProvider.TintObserver;
 import org.chromium.chrome.browser.compositor.layouts.EmptyOverviewModeObserver;
 import org.chromium.chrome.browser.compositor.layouts.OverviewModeBehavior;
 import org.chromium.chrome.browser.compositor.layouts.OverviewModeState;
-import org.chromium.chrome.browser.tabmodel.TabModelSelector;
-import org.chromium.chrome.browser.tabmodel.TabModelSelectorObserver;
-import org.chromium.chrome.browser.tabmodel.TabModelSelectorTabModelObserver;
 import org.chromium.chrome.browser.toolbar.TabCountProvider.TabCountObserver;
 import org.chromium.ui.modelutil.PropertyModel;
 import org.chromium.ui.modelutil.PropertyModelChangeProcessor;
@@ -32,10 +29,6 @@ public class TabSwitcherButtonCoordinator {
     private final PropertyModel mTabSwitcherButtonModel =
             new PropertyModel(TabSwitcherButtonProperties.ALL_KEYS);
 
-    private TabModelSelector mTabModelSelector;
-    private TabModelSelectorObserver mTabModelSelectorObserver;
-    private TabModelSelectorTabModelObserver mTabModelSelectorTabModelObserver;
-
     private ThemeColorProvider mThemeColorProvider;
     private TintObserver mTintObserver;